In the microelectronics industry, integrated circuits, such as semiconductor chips, are mounted onto packaging substrates to form modules. In high performance computer applications, these modules contain a plurality of integrated circuits. A plurality of modules are mounted onto a second level of packages such as a printed circuit board or card. The cards are inserted in a frame to form a computer.
In nearly all conventional interconnection packages except for double sided cards, signals from one chip on the package travel in a two dimensional wiring net to the edge of the package then travel across a card or a board or even travel along cables before they reach the next package containing the destination intergrated circuit chip. Therefore, signals must travel off of one module onto wiring on a board or onto wiring on a cable to a second module and from the second module to the destination integrated circuit chip in the module. This results in long package time delays and increases the wireability requirement of the two dimensional wiring arrays.
An improvement in interchip propagation time and increase in real chip packaging density can be achieved if three dimensional wiring between closely spaced planes of chips could be achieved.
U.S. patent application Ser. No. 5,099,309 describes a three dimensional semiconductor chip packaging structure which comprises a plurality of stacked cards. Each card is specially fabricated to have cavities on both sides thereof which contain chips. On each surface of the card, there are electrical conductors which are bonded by wires to contact locations on the chips. Electrical conductors extend through the cards between the chip containing regions and to contact locations on each side of the card. These contact locations have dendrites on the surface. The cards are stacked so that the dendrite covered contact locations on adjacent sides of adjacent cards intermesh to provide electrical interconnection between the adjacent cards. This structure requires a high degree board flatness for the connections to be mated.